In motorized vehicles, especially automobiles, trucks and buses, alcohol-measuring devices are used in combination with immobilizers to prevent a startup of the vehicles under the influence of alcohol. Such devices are also called (alcohol) interlock systems.
Interlock systems are known, in which, besides the alcohol-measuring device, a camera is provided, with which the test subject carrying out the measurement is photographed, and the measured result is stored together with the photo for documentation purposes (cf., for example, U.S. Pat. No. 6,748,792 B1).
A manipulation, which consists of a person who will not be the driver of the motor vehicle, which will then be able to be started, for example, a passenger, carrying out the measurement, can be revealed by means of such an interlock system, when an additional image of the driver is recorded during the drive subsequent to the alcohol measurement, and this image is compared with the image recorded during the alcohol measurement for personal identity (cf. EP 2 390 129 A1).
In addition, it is well known from EP 2 237 034 A1 that the manipulation of an interlock system can consequently be made difficult when it checks the presence of the alcohol-measuring device in a defined area of the camera field of view detecting the driver's seat during the measurement, and the release of the interlock system is linked to this condition. For this, an infrared signal, which must be detected by means of the camera within a defined camera image area, may be sent, for example, by the alcohol-measuring device. This design of an interlock system shall prevent an alcohol-measuring device, designed as a mobile hand-held device, from being used by a person other than the one sitting on the driver's seat.
When using a known interlock system having a camera, provisions are made for letting this system be read at regular service intervals, for example, monthly, in order to reveal manipulations during the measurements on the basis of the recorded and stored images. The problem with this is that it is detected comparatively late, only after the images recorded by the camera are such that identification of the persons recorded on the images, if present at all, is not possible. In particular, technical defects or a manipulation by the test subject or uncooperative behavior of the test subject may lead to the recorded images not allowing an identification. For example, the position of the camera may have been changed by manipulation or unintentionally, as a result of which this camera no longer records the predetermined area of the motor vehicle and thus also no longer the face of a test subject behaving basically as intended. Also, the camera may be out of focus, as a result of which only very blurred images not allowing a reliable personal identification were recorded and stored. On the other hand, the test subject may also elude a personal identification by shielding the subject's face in front of the camera. In both cases, it would be advantageous to be informed about the problems as early as possible in order to have the incorrect alignment or focusing of the camera corrected in the first case. The uncooperative behavior of the test subject in the second case could lead, on the other hand, to early sanctions against the corresponding users of the interlock systems which are routinely used within the framework of rehabilitation programs.